The storage of cylindrical objects presents special problems, especially if the objects are such that they need to be stored on end. This problem is exacerbated when the objects are such that their axial length (height) is substantially greater than their diameter. In this case the base cross-section upon which the objects are to rest is small compared to the lever arm from the base point to the center of mass. A classic example of this type of cylinder is a common industrial compressed gas cylinder such as those used in welding and chemical delivery systems.
In order to achieve an acceptable method of storing gas cylinders and other elongated cylindrical objects which need to be stored in a vertical orientation for usage it is necessary to provide firm support to the objects while retaining accessibility and interchangeability. This is particularly true in the case of gas cylinders since the compressed gas contained therein is depleted and the cylinders need to be replaced with new or refilled units.
Traditionally, the methods of storing cylinders tend to be in the nature of vertical racks wherein the cylinders are supported laterally at position above their centers of mass by rails or racks and are either slid or rolled into position between the rails. Typically, the structures are in the nature of a set of rails along a wall where the cylinders are placed into the storage area and then removed one at a time through the ends of the rails for usage. A chain or block prevents movement within the rack and the force of one cylinder against another prevents the devices from tipping over.
One of the problems inherent in the rack and rail standing storage system is that it tends to be a last-in-first-out ("LIFO") system. This is especially true when deliveries of cylinders are made serially rather than simultaneously. The delivery personnel and storage personnel are typically unwilling to move the rearmost cylinders to the front when new ones are delivered and typically will place the new cylinders in front of those which are already stored within the facility. This means that those in the rear are often neglected for long periods of time and can lose potency and/or become a safety hazard. Another potential problem with the standard rack and rail wall storage is that there is no specific support for the bottom portions of the cylinders. This results in potential slippage of the bottom. Although the rails prevent lateral movement of the upper portions of the cylinders it is possible to move along the axis of the rails in such a way that a cylinder may tip if it is not chained in tightly. Particularly if the bottom portion of the cylinder slides forward along the floor in the direction of the rail axis, there is a danger that even a reasonably tight chain restriction will be insufficient since very little freedom of motion is needed at the upper portion of the cylinder to permit this type of sliding. Any sliding or other free movement of the cylinder is a great potential safety hazard, especially since many of the cylinders contain hazardous materials. Additionally, this method is only viable near vertical walls and is not adapted for use in open spaces.
Another common storage facility is a horizontal arrangement storage similar to that in a soda can dispenser device wherein the force of gravity pushes the lowermost cylinder to an accessible position while upper cylinders are retained within constricting rails of a racklike device. This method has the advantage that the accessible cylinder is the one which was placed in the rack the least recently and also that the force of gravity is used to deliver the cylinder to the accessible position. However, it has the substantial disadvantage of horizontal storage, which is frequently non-optimal for use purposes. This method also has the disadvantage that the cylinders have to be lifted to a substantial height to be placed in the rack mechanism. Furthermore, since the transport of cylinders is almost exclusively in a vertical orientation there is substantial danger and opportunity for mishap in the steps of converting from the vertical to the horizontal orientation for placement in the rack mechanism.
The rolling horizontal storage system also has several inherent disadvantages. One of these is that it is not well adapted to storing cylinders of different types in the same array. That is because the bottommost cylinder is the one that must be removed before any others can be easily accessed. If this is not the cylinder desired then the user has a problem. Another difficulty is that the horizontal storage arrangement exposes the outlet valves located on the tops of the cylinders to a much greater degree of potential contact than a vertical arrangement. Since a shock to the valve area can cause accidental opening or even breaking off of the valve, thus opening the interior of the cylinder to the atmosphere and allowing the gas to escape. This is a hazard to be avoided if at all possible. This is especially true since the contents are often hazardous and since a broken top end of a cylinder may be explosively propelled at great force in the direction it is aimed. This is a further disadvantage of the horizontal array in that a laterally propelled valve mechanism stands a much greater chance of doing substantial damage to surrounding personnel and equipment than a vertically arrayed valve stem.
Various companies and individuals have made attempts to develop other methods of storing gas cylinders which provide a good balance of safety and accessibility but none of them entirely successful. Therefore, a great deal of room for improvement remains in this art.